The present invention relates to a method for removing bubbles which are attached on an inner-wall of a container made of synthetic resin and filled with a transparent or semitransparent solution, which bubbles create difficulties in inspecting the solution for extraneous substance in the container and a device thereof.
A container, such as an ampule for injection, or a glass bottle for transfusion filled with a solution for injection may contain extraneous substances such as glass chips, glanular substances, fibers or the like and the existence of these extraneous substances is a problem for quality control. Accordingly, all containers filled with a solution for injection must receive an inspection so as to pick up goods contaminated with extraneous substances.
In Japanese Pat. No. 1,123,819, Japanese Pat. No. 1,123,830 and Japanese Patent Laid-open SHO 57(1982)-142,252, there is disclosed an optical automatic inspection device for inspecting for the existence of extraneous substances contained in the container, by means of the following steps, i.e.; after rotating a container such as an ampule for injection or a bottle for transfusion solution, at high velocity, rapidly stopping the rotary movement thereof, projecting a ray of light on the solution for injection in the container, receiving the ray of light passing through the solution in the container by means of a light sensor and in case that the amount of the received light is less than a given amount, it is judged that extraneous substances exist in the container.
However, in case of a container made of synthetic resin filled with a solution, since there often exist bubbles on a surface of an inner-wall of the container it is probable that the well-known optical automatic inspecting device indicates a positive reaction by judging bubbles as an extraneous substance.
In the container filled with solution, there exist not only the solution but also a gaseous body such as air and/or nitrogen, etc, and the volume of the container is determined by both volumes of the solution and the gaseous body. In comparison with a glass bottle, in a container made of synthetic resin, a number of small gaseous bubbles are easily generated by vibration which the container received at the time of pouring the solution into the bottle or during transportation of the container, as well as further rotary movement of the container in the step of inspection of extraneous substances, or during changes in temperature which the container received in various kinds of processing environments. The generated gaseous bubbles attach upon the inner-wall of the container and it is hard to remove the bubbles entirely from the inner-wall of the container even by leaving the container at rest for a long time or by vibration, shock or the like.
When adding rotary movement at high velocity to the container in the same manner as the conventional optical automatic inspecting device, the gas existing in the upper portion of the container is incorporated in the solution to produce many gaseous bubbles in the container. On the other hard, when adding rotary movement at low velocity, the bubbles so attach to the inner-wall of the container that they cannot be removed at all.
Accordingly, when the inspection for extraneous substance is conducted on the container having many small gaseous bubbles on the inner-wall thereof, the bubbles generated by rotation float in the solution in the container and are received by the light sensor as same as extraneous substances. It is therefore provable that the container having no extraneous substances is also judged as a container having extraneous substances.